I have a Freightliner Cummins ISB 6.7 L 340 HP engine. I had been getting a check engine light and low coolant indicator followed by engine derating. Shop diagnosed bad sensor and replaced it. Several weeks later low coolant indicator followed by derating returned. Second shop diagnosed bad sensor again and replaced it under warranty. A couple days out from second replacement and check engine - low coolant is back. No derating this time. Throughout all of this - coolant is not low, temp gauge fine, no signs of overheating. Any ideas?
Broken wires in the harness plugging into the sensor? Give them a wiggle and see if you can make the warning light come on and off.
